Coos County, New Hampshire
The least populous of New Hampshire's 10 counties.
CountyFIPS 33007
- Population
- 31,343
- +108 (+0.3%) since 2020
- Land area
- 1,795
- square miles. A further 2.0% of the total area is water
- Population density
- 17.5
- people per square mile, computed rather than published
- County seat
- Lancaster
- Seat of county government.
- Established
- 1803
- 222 years ago
- Largest city
- Berlin city
- Population 9,502.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.
Satellite view
Aerial imagery of Coos County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.
Where Coos County ranks
Position among the 10 counties of New Hampshire, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.
| Measure | Value | In New Hampshire | Nationally |
|---|---|---|---|
| Population | 31,343 | 10th of 10 | 1,411th of 3,144 |
| Land area | 1,795 sq mi | 1st of 10 | 330th of 3,144 |
| Population density | 17.5 per sq mi | 10th of 10 | 2,319th of 3,144 |
| Median household income | $57,677 | 10th of 10 | 2,290th of 3,143 |
Full data for Coos County
| Measure | Value | Source and vintage |
|---|---|---|
| Population | 31,343 | Vintage 2025 Population Estimates |
| Population in 2020 | 31,235 | Vintage 2025 Population Estimates |
| 2020 estimates base? | 31,269 | Vintage 2025 Population Estimates |
| Land area | 1,795 sq mi | 2025 Gazetteer Files |
| Water area | 35.7 sq mi | 2025 Gazetteer Files |
| Total area | 1,830 sq mi | 2025 Gazetteer Files |
| Population density? | 17.5 per sq mi | Computed: Vintage 2025 estimates divided by 2025 Gazetteer land area |
| Median household income | $57,677 | American Community Survey 2020-2024 5-Year Estimates |
| Median home value | $188,900 | American Community Survey 2020-2024 5-Year Estimates |
| Median age | 50.3 | American Community Survey 2020-2024 5-Year Estimates |
| Households | 14,002 | American Community Survey 2020-2024 5-Year Estimates |
| Housing units | 20,637 | American Community Survey 2020-2024 5-Year Estimates |
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.
How the population changed
The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:
- Births minus deaths
- -315
- 211 births, 526 deaths
- Net migration
- +286
- More people moved in than moved out.
Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.
The 4 areas bordering Coos County
Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.
| Bordering area | State | Shared border | Population |
|---|---|---|---|
| Essex County | Vermont | 83 mi | 6,051 |
| Oxford County | Maine | 71 mi | 60,346 |
| Carroll County | New Hampshire | 39 mi | 52,784 |
| Grafton County | New Hampshire | 26 mi | 93,225 |
Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.
All 10 counties of New Hampshire
Open the interactive New Hampshire county map, or jump straight to any of them.
Data on this page last rebuilt 30 August 2026. How these figures are produced.